﻿using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;
using System.Linq;
using System.Web;

namespace HPIT_Library.Ashx
{
    public class ValidateCode
    {
        public ValidateCode()
         {
         }
        /// <summary>
          /// 验证码的最大长度
         /// </summary>
        public int MaxLength
         {
             get { return 10; }
        }
       /// <summary>
         /// 验证码的最小长度
        /// </summary>
        public int MinLength
        {
                 get { return 1; }
            }
        /// <summary>
       /// 生成验证码
        /// </summary>
        /// <param name="length">指定验证码的长度</param>
          /// <returns></returns>
          public string CreateValidateCode(int length)
         {
                int[] randMembers = new int[length];
             int[] validateNums = new int[length];
             string validateNumberStr = "";
             //生成起始序列值
            int seekSeek = unchecked((int)DateTime.Now.Ticks);
               Random seekRand = new Random(seekSeek);
              int beginSeek = (int)seekRand.Next(0, Int32.MaxValue - length * 10000);
                int[] seeks = new int[length];
               for (int i = 0; i < length; i++)
                     {
                        beginSeek += 10000;
                         seeks[i] = beginSeek;
                    }
              //生成随机数字
            for (int i = 0; i < length; i++)
                    {
                      Random rand = new Random(seeks[i]);
                      int pownum = 1 * (int)Math.Pow(10, length);
                      randMembers[i] = rand.Next(pownum, Int32.MaxValue);
                  }
               //抽取随机数字
             for (int i = 0; i < length; i++)
                    {
                        string numStr = randMembers[i].ToString();
                      int numLength = numStr.Length;
                 Random rand = new Random();
                    int numPosition = rand.Next(0, numLength - 1);
                      validateNums[i] = Int32.Parse(numStr.Substring(numPosition, 1));
                  }
                //生成验证码
              for (int i = 0; i < length; i++)
                    {
                       validateNumberStr += validateNums[i].ToString();
                    }
                return validateNumberStr;
            }

         /// <summary>
       /// 创建验证码的图片
       /// </summary>
        /// <param name="containsPage">要输出到的page对象</param>
        /// <param name="validateNum">验证码</param>
        public void CreateValidateGraphic(string validateCode, HttpContext context)
        {
              Bitmap image = new Bitmap((int)Math.Ceiling(validateCode.Length * 12.0), 22);
              Graphics g = Graphics.FromImage(image);
             try
            {
                      //生成随机生成器
                  Random random = new Random();
                      //清空图片背景色
                g.Clear(Color.White);
                      //画图片的干扰线
                for (int i = 0; i < 25; i++)
                          {
                                int x1 = random.Next(image.Width);
                             int x2 = random.Next(image.Width);
                              int y1 = random.Next(image.Height);
                              int y2 = random.Next(image.Height);
                               g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
                          }
                      Font font = new Font("Arial", 12, (FontStyle.Bold | FontStyle.Italic));
                        //渐变.
                LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),
                 Color.Blue, Color.DarkRed, 1.2f, true);
                      g.DrawString(validateCode, font, brush, 3, 2);
        
                 //画图片的前景干扰点
               for (int i = 0; i < 100; i++)
                           {
                             int x = random.Next(image.Width);
                              int y = random.Next(image.Height);
                             image.SetPixel(x, y, Color.FromArgb(random.Next()));
                         }
                       //画图片的边框线
               g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
                       //保存图片数据
                MemoryStream stream = new MemoryStream();
                       image.Save(stream, ImageFormat.Jpeg);
                       //输出图片流
               context.Response.Clear();
                         context.Response.ContentType = "image/jpeg";
                        context.Response.BinaryWrite(stream.ToArray());
                    }
               finally
             {
                        g.Dispose();
                      image.Dispose();
                  }
             }
         /// <summary>
         /// 得到验证码图片的长度
         /// </summary>
        /// <param name="validateNumLength">验证码的长度</param>
        /// <returns></returns>
        public static int GetImageWidth(int validateNumLength)
         {
                  return (int)(validateNumLength * 12.0);
                }
            /// <summary>
        /// 得到验证码的高度
        /// </summary>
        /// <returns></returns>
         public static double GetImageHeight()
        {
                return 22.5;
               }
}
}